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111 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Thick Filaments
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contains numerous myosin molecules
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Myosin Molecules
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which are proteins containing a rol-like tail and two globular heads (crossbridges) and tails.
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What do the heads of thick filaments interact with?
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special binding sites on the thin filaments
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Thin Filaments
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made up of globular proteins (G Actin)
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Globular Actin
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the active site on an actin in thin filaments
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What does the G Actin's active site bind to?
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myosin heads during contraction
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When contractions occur, G actins are binded and polymerized to form?
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F Actin
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What surrounds the F Actin?
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proteins called tropmyosin and troponin
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Tropomyosin
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spirals around the stiffens the F Actins
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What does Tropomyosin do?
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It covers the sctin in binding sites in a relaxed muscle
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Troponin
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binds to Ca then changes its shape in order to pull tropomyosin away from the binding sites of actin
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What are troponin's subunits?
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Tni (binds to actin), TNt (binds tropomyosin) and TNc (binds Ca)
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What are skeletal muscle cells stimulated by?
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Motor Neurons
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Axon Terminals
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The axon of each motor neuron branches extensivly to form numerous cellular extentions
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Neuromuscular junction
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the axon terminals form them with a single muscle fiber
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Synaptic cleft
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gap between the neurotransmitter and the motor end plate
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Motor End Plate
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The wrinkly part of the scarcolema
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Depolarization
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A change in membrane potential such that the cell interior becomes relatively less negative (more positive) than the cell exterior
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Action Potenial
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contraction; a wave of depolarization down the muscle
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resting membrane potential
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when the membrane junctions are closed
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Acetylcholinesterase
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the destruction of acetycloline prevents continuous contraction
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What is polarized at resting potential?
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the sarcolemma
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Refractory Period
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when muscles fibers are insensitive to further stimulation
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During contraction what is shortened and reduced
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sarcmeres shorten and z lines reduce
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What are the roles of Ca on contraction?
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makes the nerve impulse able to stimulate the muscle; cross bridges to form
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What two intercellular proteins regulate the availability of Ca to enter the cleft?
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Calsequestrin and Calmodulin
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Calsequestrin and Calmodulin
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they alternately release and bind Ca
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Myograms
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record muscle contractions
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Latent Period
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The milliseconds after a muscle is stimulated and excitation-contraction occurs
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Contraction Period
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when crossbridge formation is occuring
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What is muscle derived from?
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mesoderm
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What are the functions of muscles?
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Movement, Heat productions, Maintenance of posture, stabilize joints
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Name some examples of movement in muscles
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muscle pushes against bone for locomotion, the heart pumps blood through the blood vessles, organs propel food by peristalsis
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None
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How is heat production important to muscles?
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85% of body heat is produced by skeletal muscle contraction
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How is maitenance of posture important to muscles?
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constant contractions to counteract gravity
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What are the functional characteristics of muscle tissue?
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excitability, contractability, extensibility, elasticity
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excitability
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able to be stimulated by nervous impulses; nervous tissue only polarized membranes
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What functional characteristics have fibers?
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Contractability and Extensibility
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contractability
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able to shorten and thicken
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extensibility
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able to strech and extend
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elasticity
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able to return to original shape after being streched
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Name the types of muscle tissue
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skeletal, smooth, and cardiac muscle
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Skeletal Muscle
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Long theadlike muscle with parallel fibers
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Where are skeletal muscles found?
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attached to long bones
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How much of skeletal muscle is accounted for in the body?
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40%
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What has short contactions, quick twitch, and has non branching fibers?
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Skeletal Muscle
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Smooth muscle
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spindle shaped cells with no striations
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Where are smooth muscles found?
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in blood vessles, walls of hollow organs, and GI tract and is associated with peristalsis
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What has long contractions and a slow twitch?
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Smooth Muscle
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Cardiac Muscle
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Branched fibers with striations and intercalated disks
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Where is cardiac muscle found?
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only in the heart
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What has intermediate contraction and intermediate twitch?
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Cardiac Muscle
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Epimysium
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a sheath that covers the entire muscle
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Perimysium
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a sheath that covers each fascicle
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Endomysium
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a sheath that covers each muscle fiber
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What is in between each connective tissue dividing the endomysium?
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nerve fibers and blood vessles
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Why is muscle highly vascularized?
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because muscle uses high amounts of energy to give off large amounts of wastes and bring in more nutrients
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Where do muscles span joints and sttach to bones?
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at insertion and origin
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Indirect attachment (aponeurosis)
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muscle fascia extends beyond the muscle and anchors the muscle to the bone or to the fascia to another muscle
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Direct attachment (tendon)
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epimysium of muscle is fused to periosteum of the bone or perichondrium of cartilage
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sarcomere
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myofibrils that are divided into contractile units
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Sarcolemma
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plasma membrane
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Sarcoplasm
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cytoplasm; contains glycogen and myoglobin and higher concentrations of mitochondria than other cells
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Myoglobin
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red pigment that stores oxygen
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Sarcomere
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subdivisions of myofibril that has contractile abilities
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Sacroplasmic reticulum
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smooth ER forming interconnecting tubules surrounding myofibrils
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Terminal Cisterna
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terminal portions of the sacroplasmic reticulum adjacent to the transverse tubules; stores Ca
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Transverse Tubules
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tubules running inbetween sarcoplasmic reticulum and penetrating deeply into cells; aides in conducting stimuli into the cell
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Triads
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one T tubule and two terminal cisterna
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Name the parts of the sacromere structure
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A bands, I bands, Z bands, H zone, M line
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A Bands
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area overlapping myosin and actin filaments
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I Bands
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contains actin filaments only
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Z Bands
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seperates sarcomeres and anchors the thin filaments
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H Zone
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part of the A band that contains only myosin fibers
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M Line
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center of the H zone that holds the myosin fibers in place
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Fascicles
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largest bundles in muscles
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Muscle cells (fibers)
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divisions of fascicles
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myofibrils
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divisions of muscle cells
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myofiliments
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divisions of myofibrils
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Name the two types of contractile units
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actin and myosin
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actin
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thin filaments
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myosin
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thick filaments
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What type of muscle is innervated?
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skeletal
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Innervated
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every cell has a nerve ending
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What type of muscle has interterculated disks to control each cell
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Cardiac
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Name an example of indirect attachment
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oblique to abdominals
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Contraction Period
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when cross bridge period is forming
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relaxation period
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when Ca is no longer available and no more cross bridges occur
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Motor units
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motor neurons and all the muscle fibers that it controls
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What makes a precise contraction?
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the fewer number of fibers in a motor neuron
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What determines the strength of a contraction?
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the number of motor units being stimulated
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What are Graded Muscle Responses established on?
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the frequency of stimulation
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Twitch Contractions
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rapid, jerky contraction in response to a single stimuli
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Wave Summation
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multipule stimuli occur so there is no time to rest
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What stimulation causes larger stimulation
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wave summation
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Tetanus
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smooth sustained contractions with (unfused) or without (fused) partial relaxation
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What is the difference between wave summation and tetanus?
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Tetanus' frequency of the stimuli is much more rapid
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Treppe
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the gradual increase in the force in a contraction of a muscle caused by repetitive stimulation of the same strength after complete relaxation has occured
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Muscle Tone
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muscle that is always slightly contracted
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Name the types of muscle tone
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Isotonic Contractions and isometric contractions
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Isotonic contractions
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tone or tension remains constant; muscle length shortens decreasing the angle of the joint (shrinkage)
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How much ATP do you get with ADP and creatine phosphate?
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Three times as much creatine can be stored by the cells that ATP (good for 15 sec)
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How much ATP do you get from stored glycogen via anerobic pathways?
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glycolysis and lactic acid fermentationresulting in 2 ATP (good for 30 - 45 sec)
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How much ATP do you get by aerobic respiration?
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oxygen is required but 36 can be generated (good for 745 sec)
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Contractions
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no ATP so cross bridges can't detach
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Insufficient Oxygen
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oxygen dept
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Build up of Lactic acid
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toxic cells and must be converted back into pyruvic acid or else cramping occurs
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Heat Production (muscle fatigue)
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only 40% of energy released is useful for work; the other 60% is given off as heat
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Recruitment
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muscle contractions occur because of this; various motor neurons to a whole muscle fire asynchronously
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Isometric Contractions
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tention increases to peak tention producing capacity but the muscle neither shortens nor lengthens (no shrinkage)
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Name an example of Isometric Contraction
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ballerina
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